Purpose: Self-assessment (SA) and peer-assessment (PA) are considered useful tools in the development of lifelong learning and reflective skills. The authors implemented a teaching intervention using SA and PA amongst a large cohort of final year undergraduate students. The purpose of this study was to investigate students' perceptions of online SA and PA in order to understand the differences between these perceptions and to allow instructors to adopt differentiated instruction in developing a diverse student group's professional skills. Design/methodology/approach: The research design adopted a mixed methods approach through the use of surveys that were administered before and after the SA and peer-assessment intervention in a taxation module taught at a large public South African university. Through the use of a series of open and closed questions students' perceptions on SA and peer-assessment were analysed both quantitatively and qualitatively. Findings: The findings show that student perceptions of SA and peer-assessment differed significantly, where perceptions of SA were more positive than those towards PA. The findings indicate that SA and peer-assessment still present a challenge in an online context for large student cohorts, despite improved tracking, faster feedback and anonymity. Originality/value: The study contributes to the literature by analysing students' perceptions about SA and peer-assessment in an accounting education context and in an online setting in South Africa.